diff options
| -rw-r--r-- | src/cairo-image-info-private.h | 5 | ||||
| -rw-r--r-- | src/cairo-image-info.c | 46 |
2 files changed, 45 insertions, 6 deletions
diff --git a/src/cairo-image-info-private.h b/src/cairo-image-info-private.h index 030b1d04..6e1c4ad7 100644 --- a/src/cairo-image-info-private.h +++ b/src/cairo-image-info-private.h @@ -55,4 +55,9 @@ _cairo_image_info_get_jpx_info (cairo_image_info_t *info, const unsigned char *data, long length); +cairo_private cairo_int_status_t +_cairo_image_info_get_png_info (cairo_image_info_t *info, + const unsigned char *data, + long length); + #endif /* CAIRO_IMAGE_INFO_PRIVATE_H */ diff --git a/src/cairo-image-info.c b/src/cairo-image-info.c index e793ba51..7742c882 100644 --- a/src/cairo-image-info.c +++ b/src/cairo-image-info.c @@ -36,6 +36,12 @@ #include "cairoint.h" #include "cairo-image-info-private.h" +static uint32_t +_get_be32 (const unsigned char *p) +{ + return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3]; +} + /* Markers with no parameters. All other markers are followed by a two * byte length of the parameters. */ #define TEM 0x01 @@ -148,12 +154,6 @@ static const unsigned char _jpx_signature[] = { 0x00, 0x00, 0x00, 0x0c, 0x6a, 0x50, 0x20, 0x20, 0x0d, 0x0a, 0x87, 0x0a }; -static uint32_t -_get_be32 (const unsigned char *p) -{ - return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3]; -} - static const unsigned char * _jpx_next_box (const unsigned char *p) { @@ -239,3 +239,37 @@ _cairo_image_info_get_jpx_info (cairo_image_info_t *info, return CAIRO_STATUS_SUCCESS; } + +#define PNG_IHDR 0x49484452 + +static const unsigned char _png_magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 }; + +cairo_int_status_t +_cairo_image_info_get_png_info (cairo_image_info_t *info, + const unsigned char *data, + long length) +{ + const unsigned char *p = data; + const unsigned char *end = data + length; + + if (length < 8 || memcmp (data, _png_magic, 8) != 0) + return CAIRO_INT_STATUS_UNSUPPORTED; + + p += 8; + + /* The first chunk must be IDHR. IDHR has 13 bytes of data plus + * the 12 bytes of overhead for the chunk. */ + if (p + 13 + 12 > end) + return CAIRO_INT_STATUS_UNSUPPORTED; + + p += 4; + if (_get_be32 (p) != PNG_IHDR) + return CAIRO_INT_STATUS_UNSUPPORTED; + + p += 4; + info->width = _get_be32 (p); + p += 4; + info->height = _get_be32 (p); + + return CAIRO_STATUS_SUCCESS; +} |